The Hellfire Club are among the X-Men's most dangerous foes - and the secretive society was inspired by Britain's version of The Avengers. Marvel's version of the Hellfire Club were created by Chris Claremont and John Byrne in 1980, and they played a key role in the classic Dark Phoenix Saga. But, behind the scenes, their story is absolutely fascinating.
Unusually for superhero comics, the Hellfire Club is actually a real-world organization founded in 1718. Philip, Duke of Wharton established a club to parody popular religion and allow wealthy and influential men to engage in acts deemed to be immoral by contemporary society. Wharton's club closed its doors in 1721, but the Hellfire Club was reinvented by Sir Francis Dashwood. His version of the Hellfire Club lasted several years, but was ultimately brought down as a result of its founder being over-promoted in the British government. The image of the Hellfire Club seared its way into the British consciousness; the idea of a powerful elite who ignore the laws of men and have no sense of morality, and who treat women as nothing more than sex objects and pawns.
In 1966, the Hellfire Club was once again reinvented, this time as part of a popular British TV series called The Avengers. This starred Patrick McNee as John Steed and Diana Rigg as Emma Peel, two top secret agents who faced various fantastical foes. In the episode "A Touch of Brimstone," the Avengers infiltrated their own version of the Hellfire Club, which - while still sinister - was a whole lot more kinky. Emma Peel wound up donning a "Queen of Sin" outfit that was so controversial the episode was never aired in America, and it was edited in Britain too. X-Men writer Chris Claremont was a fan of The Avengers, and he managed to track down the episode. He loved the idea of the Hellfire Club, and soon absorbed them into X-Men lore.
Marvel's Hellfire Club are identical to the group seen in The Avengers, and Emma Peel's BDSM-style costume in "A Touch of Brimstone" is clearly the inspiration for the Black Queen costumes worn by Jean Grey in the Dark Phoenix Saga and, later, the villainous Selene. It's interesting to note, though, that the X-Men have developed the women of the Hellfire Club to make them easily superior to the men; Emma Frost, for example, uses her sex appeal as a weapon to manipulate men into doing her will. The male characters, such as Sebastian Shaw and Donald Pierce, have generally been presented as irredeemable; the women, however, have often betrayed the Hellfire Club and wound up joining the X-Men.
The modern Hellfire has ditched its classic, Claremontian kink. Instead, it's become an international corporation, responsible for shipping mutant drugs across the globe. Rather than BDSM, the Hellfire Club of 2020 has something of a pirate aesthetic, with Kate Pryde running the Marauders, the Hellfire Corporation's pirate ship.